Stan> That was exactly what I was trying to show, that you result may vary depending on data and backing device, as far as the raid1 goes it doesn't care much for the data beeing passed through it. Ben> could you try to run iostat -x 2 for a few minuts just to make sure there is no other I/O going on the device before running your tests, and then run the tests with fio instead of dd ? fio write test > fio --rw=write --filename=testfile --bs=1048576 --size=4294967296 --ioengine=psync --end_fsync=1 --invalidate=1 --direct=1 --name=writeperftest /Tommy 2013/4/22 Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>: > On 4/21/2013 2:56 PM, Tommy Apel wrote: >> Calm the f. down, I was just handing over some information, sorry your >> day was ruined mr. high and mighty, use the info for whatever you want >> to but flaming me is't going to help anyone. > > Your tantrum aside, the Intel 330, as well as all current Intel SSDs, > uses the SandForce 2281 controller. The SF2xxx series' write > performance is limited by the compressibility of the data. What you're > doing below is simply showcasing the write bandwidth limitation of the > SF2xxx controllers with incompressible data. > > This is not relevant to md. And it's not relevant to Andrei. It turns > out that the Samsung 840 SSDs have consistent throughput because they > don't rely on compression. > > -- > Stan > > >> 2013/4/21 Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>: >>> On 4/21/2013 7:23 AM, Tommy Apel wrote: >>>> Hello, FYI I'm getting ~68MB/s on two intel330 in RAID1 aswell on >>>> vanilla 3.8.8 and 3.9.0-rc3 when writing random data and ~236MB/s >>>> writing from /dev/zero >>>> >>>> mdadm -C /dev/md0 -l 1 -n 2 --assume-clean --force --run /dev/sdb /dev/sdc >>> >>> >>>> openssl enc -aes-128-ctr -pass pass:"$(dd if=/dev/urandom bs=128 >>>> count=1 2>/dev/null | base64)" -nosalt < /dev/zero | pv -pterb > >>>> /run/fill ~1.06GB/s >>> >>> What's the purpose of all of this? Surely not simply to create random >>> data, which is accomplished much more easily. Are you sand bagging us >>> here with a known bug, or simply trying to show off your mad skillz? >>> Either way this is entirely unnecessary for troubleshooting an IO >>> performance issue. dd doesn't (shouldn't) care if the bits are random >>> or not, though the Intel SSD controller might, as well as other layers >>> you may have in your IO stack. Keep it simple so we can isolate one >>> layer at a time. >>> >>>> dd if=/run/fill of=/dev/null bs=1M count=1024 iflag=fullblock ~5.7GB/s >>>> dd if=/run/fill of=/dev/md0 bs=1M count=1024 oflag=direct ~68MB/s >>>> dd if=/dev/zero of=/dev/md0 bs=1M count=1024 oflag=direct ~236MB/s >>> >>> Noting the above, it's interesting that you omitted this test >>> >>> dd if=/run/fill of=/dev/sdb bs=1M count=1024 oflag=direct >>> >>> preventing an apples to apples comparison between raw SSD device and >>> md/RAID1 performance with your uber random file as input. >>> >>> -- >>> Stan >>> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
